Portable restrooms, sometimes referred to as port-a-johns, comfort stations, etc., are commonly rented and used for special events such as parties, festivals or concerts, construction sites, and other locations where people gather temporarily. Single unit portable restrooms are common. Multi-unit portable restrooms also exist and are typically permanently installed on trailers with wheels. Such multi-unit portable restrooms are typically equipped with separate vanities, toilets, showers, etc., for each individual unit, in an effort to provide a conventional home-like bathroom on wheels. However, such multi-unit portable restrooms are expensive to procure and maintain since they involve many extra parts such as wheels, wheel bearings, wheel axles, water pumps, etc.